Hydraulic drive systems for mineral mining machines



Jan. 30, 1968 F. s. ANDERSON 3,366,016

HYDRAULIC DRIVE SYSTEMS FOR MINERAL MINING MACHINES Filed April 12, 1966 2 Sheets-Sheei 1 Jan. 30, 1968 F. s. ANDERSON 3,366,016

HYDRAULIC DRIVE SYSTEMS FOR MINERAL MINING MACHINES Filed April 12, 1966 2 Sheets-Sheet 2 United States Patent Ofiice 3,366,016 Patented Jan. 30, 1968 HYDRAULIC DRIVE SYSTEMS FOR MINERAL MINING MACHINES Forrest S. Anderson, Motherwell, Scotland, assignor to Anderson Mavor Limited, Motherwell, Scotland, a corporation of Great Britain and Northern Ireland Filed Apr. 12, 1966, Ser. No. 542,127 4 Claims. (Cl. 91-438) ABSTRACT OF THE DISCLOSURE A hydraulic drive system for driving a haulage chain includes a hydraulic motor and a hydraulic pump connected to the motor through fluid flow and return lines. A changeover control valve is interpolated into the lines which is capable of three settings, one of which causes bypassing of the hydraulic motor so that fluid flows directly to the return line from the flow line. The system further includes a valve controlled recirculation line interconnecting the fluid and control lines on the motor side of the changeover control valve and including a fluid flow restriction. The delivery of the hydraulic pump is connected so that except when the control valve is set in the bypass setting, the recirculation valve is closed through the action of the fluid from the pump on the recirculation valve closure member.

This invention is concerned with a hydraulic drive system for a mineral mining machine of the type which is intended, when in operation, to be hauled, usually along a conveyor, by the action of a chain, cable, rope, or the like, hereinafter referred to for simplicity as a chain.

According to known practice working fluid is pumped through a fluid flow line to a hydraulic motor with which the haulage chain is in engagement and which serves as the means by which the haulage of the machine along the conveyor is powered, and is exhausted therefrom, through a fluid return line, back, either directly or indirectly, to the hydraulic pump. A changeover control valve is interpolated in the fluid flow and return lines to and from, respectively, the hydraulic motor, each of the portions, of the two fluid lines, between the control valve and the hydraulic motor being a portion of the fluid flow line or a portion of the fluid return line depending on the operative setting of the control valve. Thus when the control valve is in a first operative setting one of said portions is a portion of the fluid flow line and the other of said portions is a portion of the fluid return line while, when the control valve is in a second operative setting, said one of said portions is a portion of the fluid return line and said other of said portions is a portion of the fluid flow line. The direction of rotation of the hydraulic motor, and hence the direction of travel of the machine along the conveyor, is thus dependent on the operative setting of the control valve. The control valve is also provided with an o setting in which both said portions, of the two fluid lines, between the control valve and the hydraulic motor are closed at the control valve, working fluid from the delivery of the pump being by-passed through the control valve directly from the portion of the fluid flow line on the pump side of the control valve to the portion of the fluid return line on the pump side of the control valve.

In hydraulic drive systems of the type referred to, when the control valve is moved to the OE setting the stress, in the appropriate portion of the haulage chain, which is induced during normal operation as the mining machine is traversed causes the hydraulic motor to creep in the opposite direction to that in which the motor has been rotating immediately prior to the movement of the control valve to the off setting, with resultant hydraulic leakage in the hydraulic motor. When the motor has completed a cycle of operation in this manner the strain, corresponding to said stress, in said portion of the haulage chain is suddenly relieved causing a violent movement of said portion of the chain.

It is the primary object of the present invention to provide a hydraulic drive system of the type referred to in which the disadvantages associated with this violent movement are overcome.

According to the invention a hydraulic drive system, for a mineral mining machine, comprises a hydraulic motor with which a haulage chain, cable, rope, or the like is so engageable that movement of the mineral mining machine, Which is coupled to the haulage chain, cable, rope or the like, is caused by operation of the hydraulic motor, a hydraulic pump which is connected to the hydraulic motor by a fluid flow line and a fluid return line, and a changeover control valve interpolated in the fluid flow and fluid return lines for so controlling the fluid flow in the fluid lines that, depending on the setting of the control valve, fluid in the fluid flow line is either caused to by-pass the hydraulic motor and to flow through the control valve directly to the fluid return line or is caused to flow through the hydraulic motor, the direction of said flow through the hydraulic motor, which is also controlled by the setting of the control valve, determining the direction of rotation of the hydraulic motor, in which a fluid recirculation line interconnects the fluid flow and fluid return lines on the hydraulic motor side of the control valve, a recirculation valve is incorporated .in the fluid recirculation line, and the fluid recirculation line is of restricted cross-sectional area or has incorporated therein a fluid flow restriction, the delivery of the hydraulic pump being so connected to the recirculation valve that, except when the control valve is so set as to cause the fluid flow to by-pass the hydraulic motor, the valve closure member of the recirculation valve is operatively maintained under the influence of fluid from the hydraulic pump in the position in which the valve is closed.

In a preferred embodiment of the invention the recirculation valve comprises a casing the interior of which constitutes a chamber of circular cross-section, the valve closure member, which is axially movable Within said chamber, consisting of a piston, one face of which is in communication with the delivery of the hydraulic pump and the other face of which presents a member of substantially conical form which is movable, with the piston, to a position in which said member closes a port formed in the casing. Said port and a further port, which is formed in the casing and is in communication with the face of the piston which presents the substantially conical member, communicate with the fluid recirculation line.

The hydraulic drive system may be of the open hydraulic circuit type in which a fluid reservoir is incorporated in the fluid return line between the control valve and the hydraulic pump. fluid being pumped, by the hydraulic pump, from the fluid reservoir and being returned through the fluid return line to the fluid reservoir. Alternatively the hydraulic drive system may be of the closed hydraulic circuit type in which fluid is returned through the fluid return line, directly to the hydraulic pump, there being incorporated a priming pump the suction of which is connected to a fluid reservoir and the delivery of which is connected to one of the fluid lines of the system, preferably to the low pressure fluid return line, whereby to enable fluid to be introduced into the system to compensate for any fluid leakage therefrom.

In order that the invention may be more clearly understood and more readily carried into effect the same will now, by way of example, be described more fully with reference to the accompanying drawings in which:

FIG. 1 is a diagrammatic view of a hydraulic drive system according to a first embodiment of the invention, the changeover control valve and the recirculation valve being shown in cross-section; and

FIG. 2 is a diagrammatic view of a hydraulic drive system according to a second embodiment of the invention, the changeover control valve and the circulation valve again being shown in cross-section.

With reference to both figures of the drawings, 1 denotes a hydraulic motor which is coupled through a gear train 2 to a pulley 3, a haulage chain 4, to which a mineral mining machine denoted generally by the reference is coupled, being entrained around the pulley 3 so that during operation of the motor 1 the mineral mining machine 5 is caused by the action of the haulage chain 4 to be hauled along a mineral seam in which it is operating. As will be understood a haulage cable, rope or the like may be used in place of the haulage chain 4.

A hydraulic pump 6, which is driven by an electric motor 7, is connected to the hydraulic motor 1 by way of a fluid flow line and a fluid return line, a changeover control valve denoted generally by the reference 8 being interpolated in the fluid flow and fluid return lines. Numeral 9 denotes the portion of the fluid flow line between the hydraulic pump 6 and the control valve 8, 10 denotes tie portion of the fluid return line between the control valve 8 and the hydraulic pump 6, and 11, 12 denotes the portions of the fluid flow and fluid return lines between the control valve 8 and the hydraulic motor 1, the portion 11 being a portion of the fluid flow line and the portion 12 being a portion of the fluid return line when the control valve 8 is in a first operative setting and the portion 11 being a portion of the fluid return line and the portion 12 being a portion of the fluid flow line when the control valve 8 is in a second operative setting. The control valve 8 also has an off setting intermediate the first and second operative settings, fluid in the portion 9 being caused to bypass the hydraulic motor 1 and to flow through the control valve 8 directly to the portion 10 when the control valve 8 is in the off setting.

The control valve 8, which is shown in the off setting in both figures of the drawings and which is of hitherto known construction, comprises a casing 13, a valve member 14 which is axially slidable within a passage 15 formed in the casing 13 and an operating arm 16 one end of which is pivotally connected at 17 to one end of the valve member 14 and to the other end of which the operating force is intended to be applied axially to move the valve member 14 within the passage 15, the arm 16 being pivotally connected intermediate its ends to one end of a pivot arm 18 the other end of which is pivotally connected to the casing 13. Fluid flow grooves and passages 19, only some of which are shown in the drawings, are formed in the casing 13 and in the valve member 14.

The portions 11, 12 of the fluid flow and fluid return lines are interconnected by a fluid recirculation line 20 in which is incorporated a recirculation valve denoted generally by the reference 21.

The recirculation valve 21 comprises a casing 22 the interior of which constitutes a chamber 23 of circular cross-section, and a valve closure member 24 which is axially movable within the chamber 23, the valve closure member 24 consisting of a piston 25, one face 26 of which is in communication by way of a fluid line 27 with the portion 9 of the fluid flow line and the other face 28 of which presents a member 29 of substantially conical form. The member 29, on movement of the valve closure member 24 in the appropriate direction i.e. in an upward direction as viewed in the drawings, closes a port 38 which communicates through a fluid flow restriction 31 with the portion of the fluid recirculation line 20 on one side of the recirculation valve 21. The face 28 of the piston is in communication with the portion of Cir the fluid recirculation line 20 on the other side of the recirculation valve 21 through a further port 32.

It is to be understood that the fluid flow restriction 31 may be omitted in which case the fluid recirculation line 28 is of restricted cross-sectional area.

With reference to FIG. 1 of the drawings the hydraulic drive system is of the open hydraulic circuit type in which a fluid reservoir 33 is incorporated in the portion 10 of the fluid return line, fluid being pumped, by the hydraulic pump 6 from the fluid reservoir 33 and being returned from the control valve 8 to the fluid reservoir 33.

With reference to FIG. 2 of the drawings the hydraulic drive system is of the closed hydraulic circuit type in which fluid is returned, through the portion 10 of the fluid return line, directly to the hydraulic pump 6, there being incorporated a priming pump 34 which is driven by the electric motor 7 which drives the hydraulic pump 6. The suction of the priming pump 34 is connected to a fluid reservoir 35 and the delivery of the pump 34 is connected through a one-way valve 36 to the portion 10 of the fluid return line whereby to enable fluid to be introduced into the system to compensate for any fluid leakage therefrom, the inlet to the one-way valve 36 being connected, through an excess fluid return line 37 in which is incorporated a pressure control check valve 38, back to the reservoir 35.

Referring again to both figures of the drawings, the hydraulic pump 6, when driven by the electric motor 7, pumps fluid through the portion 9 of the fluid flow line to the control valve 8, the fluid from the delivery of the hydraulic pump 6 also acting, by way of the fluid line 27 on the face 26 of the piston 25 in the recirculation valve 21 to urge the valve closure member 24 towards a position in which the member 29 closes the port 30. If the control valve 8 is in the first or second operative settings the fluid from the hydraulic pump 6 is permitted by the valve member 14 to flow through the appropriate grooves and passages 19 to the portion 11 or 12 depending on whether the control valve 8 is in the first or second operative setting.

The fluid enters the hydraulic motor 1, which is thereby driven in the appropriate direction, and is returned therefrom, through the other portion 12 or 11, respectively, to the control valve 8 and hence, by way of the portion 10 of the fluid return line, to the hydraulic pump 6 either directly, with reference to FIG. 2 of the drawings, or by way of the fluid reservoir 33, with reference to FIG. 1 of the drawings.

The fluid in the portions 11, 12 of the fluid flow and return lines is applied by way of the fluid recirculation line 20 to the member 29, through the flow restriction 31, and to the face 28 of the piston 25. The pressures thereby acting on the member 29 and on the face 28 of the piston 25 tend to urge the member 29 away from the position in which the port 30 is closed by the member 29 but since the force exerted on the face 26 of the piston 25 is greater than the combined forces exerted by the pressures on the member 29 and on the face 28 of the piston 25 the port 30 remains in the closed position.

When now the control valve 8 is moved to the off setting, thereby closing the portions 11, 12 of the fluid flow and return lines at the control valve 8 and causing the fluid from the delivery of the hydraulic pump 6 to flow through the control valve 8 directly to the portion 18 of the fluid return line so reducing the pressure thereof, the force exerted on the member 29 or on the face 28 of the piston 25, depending on which of the portions 11, 12 has been a portion of the fluid flow line, urges the piston 25, and the member 29, to move to a position in which the port 30 of the recirculation valve 21 is no longer closed by the member 29. Fluid may thus flow from portion 11 or 12 to the portion 12 or 11, respectively, through the fluid recirculation line 20 and the recirculation valve 21, as the hydraulic motor 1 rotates in the appropriate direction under the influence of the stress in the haulage chain 4 and until said stress is relieved, the

fluid flow restriction 31 determining the rate of said flow.

In this manner the sudden and violent movement of the haulage chain 4 as the stress in the haulage chain 4 is relieved is substantially avoided thereby substantially overcoming the disadvantages associated with this movement.

What is claimed is:

1. A hydraulic drive system, for a mineral mining machine, comprising a hydraulic motor which is adapted to be engaged by a haulage element for movement of said mineral mining machine, to which said haulage element is adapted to be coupled, on operation of said hydraulic motor, a hydraulic pump, a fluid flow line and a fluid return line connecting said hydraulic pump to said hydraulic motor, and a change-over control valve interpolated in said fluid flow and fluid return lines for controlling the fluid flow in said fluid lines, said control valve having three operative settings in the first of which fluid in said fluid flow line is caused to by-pass said hydraulic motor and to flow through said control valve directly to said fluid return line, in the second of which fluid in said fluid flow line is caused to flow in one direction through said hydraulic motor thereby to cause rotation of said hydraulic motor in one direction, and in the third of which fluid in said fluid flow line is caused to flow in the opposite direction through said hydraulic motor thereby to cause rotation of said hydraulic motor in the opposite direction, in which a fluid recirculation line interconnects said fluid flow and fluid return lines on the hydraulic motor side of said control valve, a recirculation valve is incorporated in said fluid recirculation line, and fluid flow restrictive means is incorporated in said fluid recirculation line, said hydraulic pump having a delivery which is connected to said recirculation valve for causing said recirculation valve to be maintained, under the influence of fluid from said hydraulic pump, in the condition in which said valve is closed other than when said control valve is in said first of said three operative settings.

2. A hydraulic drive system according to claim 1 in which said recirculation valve comprises a casing having an interior constituting a chamber of circular cross-section, said valve closure member, which is axially movable Within said chamber, consists of a piston having a first face which is in communication with said delivery of said hydraulic pump and a second face, a member of substantially conical form is presented by said second face, a port is formed in said casing and is closable by said member of substantially conical form on movement of said member with said piston, a further port is formed in said casing and is in communication with said second face of said piston, and said port and said further port communicate with said fluid recirculation line.

3. A hydraulic drive system according to claim 1 in which a fluid reservoir is incorporated in said fluid return line between said control valve and said hydraulic pump.

4. A hydraulic drive system according to claim 1 including a priming pump having a suction and a delivery, and a fluid reservoir to which said suction of said priming pump is connected, said delivery of said priming pump being connected to one of said fluid lines of said system for the introduction of fluid into said system to compensate for any fluid leakage therefrom.

References Cited UNITED STATES PATENTS 2,179,179 11/1939 Fischel et al 9l-437 2,219,967 10/1940 Thiry 9l--437 2,424,288 7/1947 Severy 91-438 XR 2,667,181 1/1954 Ashton et al 91-438 XR EDGAR W. GEOGHEGAN, Primary Examiner. 

